Reduced diameter stent/graft deployment catheter

ABSTRACT

A reduced diameter stent/graft deployment catheter and a method of insertion for said catheter. The delivery sheath portion of the catheter, i.e. the distal portion of the catheter containing the stent/graft, has a larger outer diameter than the remaining proximal portion of the catheter. The reduced outer diameter of the body of the catheter allows for the use of a smaller diameter introducer sheath. The method of inserting said catheter comprises the following steps: First, the delivery sheath portion of the catheter is inserted into the patient. Next, an introducer sheath, with an outer diameter which is no larger than the outer diameter of the delivery sheath, is disposed about the catheter and its distal portion inserted into the patient. The catheter is then advanced into the patient and the stent/graft deployed.

This is a continuation of application Ser. No. 09/541,215, filed Apr. 3,2000, now U.S. Pat. No. 6,306,145, which is a continuation ofapplication Ser. No. 09/006,113, filed Jan. 13, 1998, now U.S. Pat. No.6,074,398.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a stent/graft deployment catheter, particularlyfor repairing defects in arteries and other lumens within the body. Moreparticularly, the invention relates to a reduced diameter stent/graftdeployment catheter for delivering a stent/graft in situ for repairingdefective body lumens, aneurysms, and particularly abdominal aorticaneurysms.

2. Description of the Prior Art

An abdominal aortic aneurysm (AAA) is a sac caused by an abnormaldilatation of the wall of the aorta as it passes through the abdomen.The aorta is the main artery of the body, supplying blood to all organsand parts of the body except the lungs. It arises from the leftventricle of the heart, passes upward, bends over and passes downthrough the thorax and through the abdomen, and finally divides into theiliac arteries which supply blood to the pelvis and lower extremities.

The AAA ordinarily occurs in the portion of the aorta below the kidneys.When left untreated, the aneurysm will eventually cause the sac torupture with ensuing fatal hemorrhaging in a very id short time. Therepair of abdominal aortic aneurysms has typically required majorabdominal surgery in which the diseased and aneurysmal segment of theaorta is bridged with a prosthetic device, such as a synthetic graft.

As with all major surgeries, there are many disadvantages to the abovementioned surgical technique, the foremost of which is the highmortality and morbidity rate associated with surgical intervention ofthis magnitude. Other disadvantages of conventional surgical repairinclude the extensive recovery period associated with such surgery;difficulties in suturing the graft to the aorta; the unsuitability ofthe surgery for many patients, particularly older patients exhibitingcomorbid conditions; and the problems associated with performing thesurgical procedure on an emergency basis after the aneurysm has alreadyruptured.

In view of the above mentioned disadvantages of conventional surgicalrepair techniques, techniques have been developed for repairing AAAs byintraluminally delivering an aortic graft to the aneurysm site throughthe use of a catheter based delivery system, and securing the graftwithin the aorta using an expandable stent. Since the first documentedclinical application of this technique was reported by Parodi et al. inthe Annals of Vascular Surgery, Volume 5, pages 491-499 (1991), thetechnique has gained more widespread recognition and is being used morecommonly. As vascular surgeons have become more experienced with thisendovascular technique, however, certain problems have been encountered.One major problem involves the stiffness of the catheter body. Surgeonshave encountered difficulty in navigating the prior art catheter throughthe vessel tree of a patient. Therefore, the need exists for astent/graft deployment catheter capable of being more easily navigatedthrough the vessel tree of a patient.

Use of the stent/graft deployment catheter eliminates the problem ofsuturing the graft to the aorta associated with surgical repairtechniques. However, use of the catheter still requires a cut-downsurgery to locate and expose the blood vessel and thus the patientrecovery time is still quite long. Therefore, the need exists for astent/graft deployment catheter which can be inserted percutaneouslyinto the blood vessel of the patient. A percutaneous procedure wouldavoid the surgery necessary to locate the blood vessel and therebydecrease patient recovery time significantly. The presence of such acatheter on the market may finally allow for the full transition fromthe currently used surgical cut-down method of stent/graft insertion tothe much preferred percutaneous insertion method. Such a catheter hasnot appeared on the market yet because of the difficulty inherent indesigning a catheter small enough to be inserted percutaneously. Thepresent invention does not disclose such a catheter. Rather the presentinvention recognizes the ever existing need for smaller catheters andtherefore discloses a catheter design which can be used to decrease thediameter of any catheter on the market including eventually a catheterappropriately sized for percutaneous insertion.

Large catheters are also problematic because they require large sizeinsertion holes which are traumatic to the blood vessel and whichrequire surgery to repair. Therefore, the need exists a smaller sizecatheter which may be inserted through a reduced diameter insertion holein the blood vessel.

Another problem with the use of a stent/graft deployment catheter,regardless of whether it is introduced percutaneously or via thesurgical cut-down method, is that its presence in the blood vesselduring the stent/graft deployment procedure restricts blood flow in theblood vessel. Therefore, the need exists for a stent/graft deploymentcatheter which minimizes the amount of blood flow restriction during thestent/graft deployment procedure.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to produce a reduceddiameter flexible stent/graft deployment catheter which would allow foreasier navigation through often tortuous arteries and also for a smallerinsertion hole in the femoral artery.

It is another object of the invention to produce a method for insertionof said reduced diameter flexible stent/graft deployment catheter.

It is still another object of the invention to produce a reduceddiameter stent/graft deployment catheter which minimizes the amount ofblood flow restriction in the catheter occupied blood vessel.

The invention is a reduced diameter stent/graft deployment catheter anda method of insertion for said catheter. The delivery sheath portion ofthe catheter, i.e. the distal portion of the catheter containing thestent/graft, has a larger outer diameter than the remaining proximalportion of the catheter. The reduced outer diameter of the body of thecatheter allows for the use of a smaller diameter introducer sheath. Themethod of inserting said catheter comprises the following steps: First,the delivery sheath portion of the catheter is inserted into thepatient. Next, an introducer sheath, with an outer diameter which is nolarger than the outer diameter of the delivery sheath, is disposed aboutthe catheter and its distal portion inserted into the patient. Thecatheter is then advanced into the patient and the stent/graft deployed.

To the accomplishment of the above and related objects the invention maybe embodied in the form illustrated in the accompanying drawings.Attention is called to the fact, however, that the drawings areillustrative only. Variations are contemplated as being part of theinvention, limited only by the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like elements are depicted by like reference numerals.The drawings are briefly described as follows.

FIG. 1 is longitudinal cross section of a distal portion of a prior artstent/graft deployment catheter.

FIG. 2 illustrates a longitudinal cross section of the prior artcatheter of FIG. 1 percutaneously inserted into a patient's bloodvessel.

FIG. 3 is longitudinal cross section of a distal portion of an improvedreduced diameter stent/graft deployment catheter.

FIG. 4 illustrates a longitudinal cross section of the inserted improvedcatheter of FIG. 3 after the insertion sheath has been inserted into thepatient.

FIG. 5 illustrates a longitudinal cross section of the inserted improvedreduced diameter catheter of FIG. 3 after the stent/graft has expandedand the tip has been pulled through the stent/graft lumen.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a longitudinal cross section of a co-axial prior artstent/graft deployment catheter. Said catheter is comprised of acatheter body 10, a tip 50, an inner tube 40, a stent/graft 30, and aplunger 20, all of which are co-axial and have proximal and distal ends.Only the distal portion of the deployment catheter is shown for clarity.The catheter body 10 is slidingly disposed about the inner tube 40 andhas a delivery sheath portion 42, a tube portion 43, and an innersurface 70. The plunger 20 is slidingly disposed about the inner tube 40and is slidingly disposed within the catheter body 10. The distal end ofthe inner tube 40 is attached to the tip 50. The stent/graft isslidingly disposed about the inner tube 40 and within the deliverysheath portion 42 of the catheter body 10 and is between the proximaland of the tip stand the distal end of the plunger 20. The stent/graft30 has an outer surface 60 and a lumen 52 extending from its proximalend to its distal end. The stent/graft lumen 52 is occupied by a distalportion 41 of the inner tube 40. The delivery sheath portion 42 of thecatheter body 10 is located between the tip 50 and the tube portion 43of the catheter body 10. The inner and outer diameters of the deliverysheath portion 42 and the tube portion 43 are the same.

The stent/graft deployment catheter may be inserted percutaneously orvia a surgical cut-down method into a blood vessel. FIG. 2 illustrates alongitudinal cross section of the prior art catheter percutaneouslyinserted in a blood vessel 55 of a patient 54. The delivery sheathportion 42 of the catheter is still down stream of an aneurysm 56 inneed of repair and has fully exited an introducer sheath 57. If insertedpercutaneously, as illustrated in FIG. 2, a guide wire 58 is firstadvanced through an insertion site 53 into the blood vessel 55 of thepatient 54. Next, a dilator sheath assembly (dilator not shown) isdisposed about the guide wire 58 and the distal portion of the dilatoris used to dilate the insertion site 53. After dilation of the insertionsite 53 the dilator is removed while the insertion sheath 57 is held inplace in the blood vessel 55 of the patient 54. Next, the catheter isinserted into the introducer sheath 57 and is advanced forward into theblood vessel 55 of the patient 54. Upon proper positioning of the tip 50in the blood vessel 55 the plunger 20 is held in place while thecatheter body 10 is pulled away from the tip 50 exposing the entirestent/graft 30 to blood. Upon contact with blood the stent/graft 30expands such that the diameter of the stent/graft lumen 52 becomeslarger than the outer diameter of the tip 50. The expanded stent/graft30 becomes fixed in place in the blood vessel 55 and thus bridges theaneurysm. The inner tube 40 is then pulled away from the stent/graft 30such that the tip 50 passes through the stent/graft lumen 52. Finally,the catheter is removed from the patient 54. Note that there are manyother types of self-expandable stent/grafts on the market including heatsensitive and spring-like stent/grafts. Note further that one majorfunction of the introducer sheath 57 is to control bleeding at theinsertion site 53 of the patient 54 during the entire procedure.

FIG. 3 illustrates a longitudinal cross section of an improved reduceddiameter stent/graft deployment catheter. Said catheter is comprised ofa catheter body 10, a tip 50, an inner tube 40, a stent/graft 30, and aplunger 20, all of which are co-axial and have proximal and distal ends.Only the distal portion of the deployment catheter is shown for clarityThe catheter body 10 is slidingly disposed about the inner tube 40 andhas a delivery sheath portion 42, a tube portion 43, and an innersurface 70. The plunger 20 is slidingly disposed about the inner tube 40and slidingly disposed within the catheter body 10. The distal end ofthe inner tube 40 is attached to the tip 50. The stent/graft 30 isslidingly disposed about the inner tube 40 and within the deliverysheath portion 42 of the catheter body 10 and is located between the tip50 and the distal end of the plunger 20. The stent/graft 30 has an outersurface 60 and a lumen 52 extending from its proximal end to its distalend. The stent/graft lumen 52 is occupied by a distal portion 41 of theinner tube 40. The delivery sheath portion 42 of the catheter body 10 islocated between the tip 50 and the tube portion 43 of the catheter body10. The outer and inner diameters of the tube portion 43 of the catheterbody 10 are smaller than the outer and inner diameters of the deliverysheath portion 42 of the catheter body 10, respectively. The plunger 20has a delivery sheath portion 44 and a tube portion 45.

Similar to the prior art catheters, the reduced diameter stent/graftdeployment catheter may be inserted percutaneously or via a surgicalcut-down method into a blood vessel. FIG. 4 illustrates a longitudinalcross-section of a reduced diameter introducer sheath 57 and an improvedreduced diameter stent/graft deployment catheter percutaneously insertedin a blood vessel 55 of a patient 54. The delivery sheath portion 42 ofthe catheter is still down stream of an aneurysm 56 in need of repairand is inserted before an introducer sheath 57. If insertedpercutaneously, as illustrated in FIG. 4, a guide wire 58 is firstadvanced through an insertion site 53 into the blood vessel 55 of thepatient 54. Next, a dilator (not shown) is disposed about the guide wire58 and its distal portion is used to dilate the insertion site 53. Afterremoval of the dilator the catheter is disposed about the guide wire 58and is advanced into the blood vessel 55 such that the entire deliverysheath portion 42 is enveloped by the blood vessel 55. The reduceddiameter introducer sheath 57 is then disposed about the tube portion 43of the catheter body 10 and is advanced forward such that its distal aportion 51 is inserted into the blood vessel 55. The outer diameter ofthe introducer sheath 57 is about the same as the outer diameter of thedelivery sheath portion 42 of the catheter body 10. Thus inserting thedelivery sheath portion 42 into the blood vessel 55 first, beforeinserting the introducer sheath 57, allows for the use of a smallerintroducer sheath. The introducer sheath 57 must be large enough only toaccommodate the tube portion 43 of the catheter body 10. Next, thecatheter is advanced forward into the blood vessel 55 of the patient 54.Upon proper positioning of the tip 50 in the blood vessel 55 the plunger20 is held in place while the catheter body 10 is pulled back away fromthe tip 50 exposing the entire stent/graft 30 to blood. Upon contactwith the patient's blood the stent/graft 30 expands such that thediameter of the stent/graft lumen 52 is larger than the outer diameterof the tip 50. The expanded stent/graft 30 becomes fixed in place in theblood vessel 55 and thus bridges the aneurysm. Next, the inner tube 40is pulled away from the stent/graft 30 such that the tip 50 passesthrough the stent/graft lumen 52. FIG. 5 illustrates a longitudinalcross section of the inserted improved reduced diameter catheter afterthe stent/graft 30 has expanded and the tip 50 has been pulled throughthe stent/graft lumen 52. Finally, the introducer sheath 57 and thendeployment catheter is removed from the patient 54.

What is claimed is:
 1. A method for deploying a medical device withinvasculature using a system including a catheter and a plunger, thecatheter having a delivery sheath portion that substantially mates witha delivery sheath portion of the plunger, the delivery sheath portion ofthe catheter having a larger diameter than remaining portions of thecatheter, comprising: gaining access to vasculature; advancing thesystem to a target site within vasculature; causing relativelongitudinal motion between the plunger and the catheter; deploying themedical device at the target site by engaging the medical device withthe delivery sheath portion of the plunger; withdrawing the plunger sothat it substantially mates with the delivery sheath portion of thecatheter; and removing the system from the vasculature; wherein thesystem further includes an inner tube slidably disposed in the catheterand further comprising translating the inner tube longitudinallyindependently of the plunger beyond a terminal end of the catheter. 2.The method of claim 1 wherein the system includes a guidewire slidablyreceived within the inner tube and further comprising placing theguidewire within the vasculature.
 3. The method of claim 2, furthercomprising configuring the guidewire across the target site.
 4. Themethod of claim 3, further comprising advancing the catheter and plungerover the guidewire to the target site.
 5. The method of claim 4, whereinthe system includes a introducer sheath sized to receive the deliverysheath and further comprising configuring the system for placementwithin vasculature by coaxially arranging the introducer sheath aboutthe delivery sheath and the delivery sheath about the plunger and innertube.
 6. The method of claim 4, further comprising employing theintroducer sheath to dilate an insertion site into which the system isadvanced.
 7. The method of claim 6, further comprising removing theintroducer sheath while leaving the delivery sheath in place in thevasculature.
 8. The method of claim 1, wherein the medical device isself-expanding.
 9. The method of claim 1, wherein the medical device isa stent/graft.
 10. The method of claim 1, wherein the system includes anintroducer sheath and further comprising introducing the introducersheath within vasculature subsequent to placement of the delivery sheathinto vasculature.
 11. The method of claim 1, wherein the plunger isadvanced with respect to the catheter.